Hello and welcome to the site.
I have a bonsai at my home but sorry I don't know which tree is it.
This presents a bit of a problem, it is very difficult to make suggestions without knowing the species. Here is some information regarding [url=https://www.helpfulgardener.com/forum/viewtopic.php?t=3557]taking and posting pictures.[/url] We may be able to identify it for you. Can you inquire where it was purchased?
Does bonsai tree show the effect of seasons
It depends. If the tree in question is a temperate deciduous species like Maple it will go through the same cycle as a Maple in the ground. (Bonsai is primarily an outdoor activity) A temperate evergreen such as a Juniper will not show such marked differences with the passing of the seasons but still needs to experience them to thrive. Tropicals are different still in that they have no dormant period as such but still have a rhythm that they follow, some more than others. So there really is no easy answer to that question.
My plant leaves are going yellow day by day.there are more 30 to 35 leaves left .I am seeing 4 to 5 leaves falling daily... is this a problem with the plant or just the effect of spring season as all plants outside show the effect?
Yes this is a problem. You should not be experiencing yellowing leaves in the springtime, they should be healthy and vibrant, although it may be a little early in the season. How long have you had it and how have you been keeping it?
I keep the plant out in sun for atleast three hours daily
If by this you mean that you are moving it inside then please don't. If you are moving it around outside I still suggest that you do not. Find a good spot for it outside leave it there. If you are concerned about too much sun choose a location that gets sun in the morning and filtered sun in the afternoon.
If it is a tropical plant then this advice may not be appropriate yet as it may still be too cold, especially in the evenings. My tropicals stay outside once the weather will allow it, they are still outside. A proper identification is essential in determining how to handle your tree.
and water it daily.
There is an excellent chance that this is the root of the problem. Never water any potted plant on any kind of a schedule. Depending on the temperature and the type of soil it is in, etc, etc, once a day may very well be too often right now. This can, of course, vary with the season. Please read the general growing sticky located at the top of the forum for information on proper watering. Can you describe the soil as this plays a large role in the frequency of watering? Is it finely textured and peaty or coarse and gritty?
there is atray below it and some of the roots are coming out.so do I need to cut them
Yes go ahead and snip them off this will not harm your tree although this may be an indication that it is root-bound. Ensure that no water can ever wick back up into the pot.
I hope that this begins to answer some of your questions.